SUPPLY CHAIN Developments in Electronic


Temperature and Time Indicators Temperature and time indicators play an important part in ensuring quality of supply for sensitive products in sectors such as food and pharmaceuticals.


W


hile liquid-based indicators have long provided a simple, reliable approach to monitoring for over-temperature or extended duration, electronic indicators have now come into their own. Electronic ‘smart labels’ offer greater accuracy and the possibility of data capture. Three examples of low cost electronic indicators are as follows.


Temperature and time indicators Small, low cost indicators travel with goods during transport and storage to alert supply chain professionals to any breach in temperature limits, either above or below specification; they can also indicate the cumulative duration of breaches. The latest generation of electronic indicator is very small and lightweight (around 6g), offering accuracy of better than 0.5 degC, with low cost. Their size makes them suitable for temperature monitoring at pack level, making them versatile, go-anywhere electronic indicators for a wide range of applications. Common temperature ranges for monitoring include freezing and fridge, with real-time temperature tracking and visual alerts for any breaches in expected conditions. Goods are monitored throughout their entire journey and storage. During the recent pandemic, tracking vaccines from manufacture, storage at extremely low temperatures, through to distribution and use in clinics became a high priority.


In some cases, time itself is more important; freshness dating and service reminders are two good examples. In these cases, ‘smart label’ indicators can be configured to monitor time from a few minutes to several years.


Multiple use temperature and time indicators


Recently, a form of multiple-use temperature indicators has appeared. These can be reset and reused several times, reducing the cost per use and simplifying inventory control. By avoiding the need to dispose of indicators after each use, resettable indicators represent a move towards sustainability. In one such product range, to read the temperature indicator, LED lamps on the face of the device clearly show if a


42 MAY 2024 | ELECTRONICS FOR ENGINEERS


Micro Data Loggers


temperature breach has occurred. In the standard configuration, if the temperature has exceeded 5 degrees C for more than 40 seconds, the Amber ‘Instant’ light will flash; should the breach last for more than 15 minutes cumulative, the Red ’15min’ LED will flash.


Resetting the device is achieved using a special reset device from the supplier and the indicator is ready for immediate re-use up to five times.


Scanning a QR code on the front of the indicator allows the user to access a calibration certificate for quality assurance purposes.


The food industry, pharmaceuticals, healthcare, chemicals and logistics all make use of electronic temperature indicators to help monitor and maintain the integrity of products and to support their quality assurance processes.


Traditional temperature data loggers for shipping are relatively expensive, and usually require computer software and training to use. Where there is a need for constant logging over long periods, this expense can be justified, but a new breed of ‘Micro Data Logger’ has emerged that is both more compact and economical. These devices are capable of providing an immediate irreversible indication of over and under-temperature conditions using built-in LED lamps, yet can also allow users to download stored temperature data wirelessly to an accompanying app for analysis and filing using built-in NFC technology. Where the logged data is not required for analysis, the indicator can be discarded, and does not need to be returned to base.


Simple micro data loggers are ideal for refrigerated temperature shipping. One such model can log and store up to 3800 temperature data points, and the alarm status is always visible. Temperature breaches can be investigated by downloading logged data using an NFC enabled smartphone via a temperature monitoring app (iOS or Android) to any Internet connected device. Nora Murphy, Commercial Director of Timestrip UK.


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